In a power conversion device, the loss in a power semiconductor is reduced because the speed of a switching operation is increased by technological innovations in the field, of power semiconductors used in a power semiconductor module, which is a main component of the power conversion device. Thus, a cooler for cooling the power semiconductor module can be downsized. As a result, the power conversion device is downsized. In particular, a UPS (Uninterruptible Power Supply) having the power conversion device is installed in an urban neighborhood where land prices are high, and is used for a data center. Therefore, it is preferred that the footprint of the power conversion device be small. Further, when power semiconductor modules forming a power conversion circuit in the power conversion device are connected in parallel and used to output a rated current, it is preferred that the currents flowing in the individual power semiconductor modules be balanced.
There is a well-known power conversion device that balances the currents flowing in parallel-connected power semiconductor modules. According to Patent Literature 1, a plurality of power semiconductor modules are arrayed so that their lateral surfaces are parallel to each other with respect to the direction in which terminal sections provided for the power semiconductor modules are arrayed. The power semiconductor modules are connected by an alternating-current conductor and a multilayer board formed of a positive conductor and a negative conductor. Further, the currents flowing in the individual power semiconductor modules are balanced by forming a cut-out portion in the alternating-current conductor.